Comprehensive mass spectrometric analysis of novel organic semiconductor molecules.

摘要

This work presents a comprehensive mass spectrometry (MS) study of novel organic semiconductor molecules including ion mobility/reactivity measurements and trace elemental analysis. The organic molecules investigated here are important semiconductor materials for molecular electronic devices such as Organic Field-Effect Transistors (OFETs) and Light Emitted Diodes (LED).; A high-performance orthogonal time-of flight mass spectrometer (TOF-MS) in combination with a matrix assisted laser desorption/ionization (MALDI) source operating at elevated pressure was used to perform MALDI/TOF analyses of pentacene and some of its derivatives with and without an added matrix. The observation of ion-molecule reactions between "cold" analyte ions and neutral analyte molecules in the gas phase has provided some insight into the mechanism of pentacene cluster formation and its functionalized derivatives. Furthermore, some of the matrices employed to assist the desorption/ionization process of these compounds were observed to influence the outcome via ion-molecule reactions of analyte ions and matrix molecules in the gas phase. The stability and reactivity of the compounds and their clusters in the MALDI plume during gas-phase expansion were evaluated; possible structures of the resulting clusters are discussed. The MALDI/TOF technique was also helpful in distinguishing between two isomeric forms of bis-[(triisopropylsilyl)-ethynyl]-pentacene.; Furthermore, we reported ion mobility measurements of functionalized pentacene ions with a modified triple quadrupole mass spectrometer fitted with an ion molecule reactor (IMR). The IMR is equipped with a variable axial electrostatic drift field (ADF) and is able to trap ions for a prolong period of time. These capabilities were successfully employed in the measurement of ion mobilities in different modes of the IMR operation. Theoretical modeling of the drift dynamics and the special localization of the large ion packet was successfully implemented. The contribution of the quadrupole RF field to the drift dynamics also was taken into consideration.; The IMR was successfully employed in the ion-molecule reactions study of four functionalized pentacene derivatives such as TIPS, o-TIPS, 6,13-bis-[(triisopropylsilyl)-ethynyl]-pentacene-2,3-dicarbonitrile (TIPS(CN)2), and 6,13-bis-[(triisopropylsilyl)-ethynyl]-pentacene-2,3,9,10-tetracarbonitrile (TIPS(CN)4). Details of the IMR operation in this mode are extensively discussed.; The purity of the starting material is one of the most important parameters for the fabrication of a molecular electronic device. We report the method of determination of trace elemental impurities (Li, Na, Al, Mg, Be, Pb, Mn, Co, Ti, Sn, Cu, Cr, V, Zn, Fe, Ca, K and Ni) in organic semiconductor materials, such as Tetracene, Anthracene, Pentacene, TIPS and Rubrene, using an inductively coupled plasma quadrupole mass spectrometer (ICP-MS) fitted with a dynamic reaction cell (DRC). The determination of Fe, Ca, K and Ni in the organic semiconductor materials was carried out using NH3 as a reaction gas in the DRC mode to obviate the effect of polyatomic isobaric interferences. The other trace elements such as Li, Na, Al, Mg, Be, Pb, Mn, Co, Ti, Sn, Cu, Cr, V and Zn have been determined under standard operating conditions.